Presently, for patients suffering from cerebral and/or peripheral vascular disease, an interventional neuroradiologist/neurosurgeon has three main embolic device choices: platinum coils, hydrogel/platinum coils, or degradable polymer/platinum coils. All three types of coils are deployed into aneurysms and have advantages and disadvantages associated with them. Platinum coils are easy to deploy through standard microcatheters, are available in wide ranges of softness, and are best suited for aneurysms with small sizes or necks. Hydrogel/platinum coils are also easy to deploy through standard microcatheters. Although hydrogel/platinum coils are relatively stiffer than platinum coils and can be challenging to deploy inside aneurysms, they give acceptable results in a broader range of sac and neck sizes. Degradable polymer/platinum coils are easily tracked and deployed into aneurysm sacs; however, they only give acceptable results in aneurysms with small sizes or necks.
Despite the three coil varieties, there exists an unmet clinical need for embolic devices that deploy easily into aneurysm sacs (like platinum coils) and result in durable occlusion in a wide variety of aneurysm sizes (like hydrogel/platinum coils). Among the benefits of the apparatus and methods of the present description is a device that tracks through a microcatheter with less friction than a platinum coil, deploys in the aneurysm sac like the softest platinum coil on the market, expands like the hydrogel/platinum coils, and provides durable occlusion of the aneurysm sac, while permitting the interventional neuroradiologist/neurosurgeon, or surgeon, to use standard microcatheters and other associated equipment.
The improved durability of hydrogel/platinum coils is believed to be a result of the increased volumetric filling of the aneurysm sac and the resulting increase in stability of the coil mass. A current version of the hydrogel/platinum coil has an overcoil which limits the expansion of the hydrogel. In preclinical models, while current overcoiled hydrogel/platinum coils provide better results than platinum coils, it is believed that a non-overcoiled hydrogel device would be less stiff than current overcoiled versions. The present description provides an embolic device that is capable of providing increased volumetric filling, more so than both platinum coils and overcoiled hydrogel/platinum coils, with less stiffness than overcoiled hydrogel/platinum coils.
In large and giant aneurysms, inflammatory complications can occur, presumably due to the large amount of thrombus formation and organization. It is believed that with the increased volumetric filling of the aneurysm sac provided by the hydrogel, decreased thrombus formation and organization occurs and presumably fewer inflammatory complications result. The present description provides an embolic device which could reduce inflammatory complications.
An uncommon, but potentially dangerous, complication occurs when a coil gets interlocked within the winds of the coil itself. In this case, one can neither push nor pull the coil while keeping the device intact within the aneurysm site. The only option is to pull back and unwind the coil from the aneurysm site to the groin. The potentially dangerous result is a stretched coil. Although stretch resistant coils have been developed, this complication has not been eliminated, and still poses a dangerous threat to a patient. It is believed that the device of the present description eliminates this complication altogether.